Prop Backpack impedance and voltage issues
Chris B.
Posts: 18
I'm working with a Prop Backpack. I don't have a proper vid source at the moment so I'm using a Prop Demo Board. Let me know if that fact is actually my problem... This isn't my working configuration anyway, just how I'm testing my software on the bench.
The symptom is:
When I plug into just my Axis video server (signal destination), the overlaid text is essentially invisible, can't tell that it's there (except when it obscures the picture behind it, and still not readable). Can only see the Graphics Demo running on the Demo Board.
When I plug into just my handheld LCD NTSC monitor, the overlaid text is readable but "dim".
When I plug into the LCD monitor and Axis video server in parallel (double (37.5 ohm) termination), then the text on the LCD monitor is "bright" and looks like I expect it to look, but on the Axis video server, the text is more visible yet still unreadably dim.
So, my next check is to try a legitimate source, like a lipstick cam, which I'm going to try later today when I can get my hands on the camera.
Would the easiest fix, if the Demo Board is the problem, to put an op amp on the breadboard to drive the video out? I could also try an op amp on the output of the backpack. Is there a chip that is a self contained video amp with the proper impedances so I don't have to add external resistors, etc?
Thanks,
Chris
The symptom is:
When I plug into just my Axis video server (signal destination), the overlaid text is essentially invisible, can't tell that it's there (except when it obscures the picture behind it, and still not readable). Can only see the Graphics Demo running on the Demo Board.
When I plug into just my handheld LCD NTSC monitor, the overlaid text is readable but "dim".
When I plug into the LCD monitor and Axis video server in parallel (double (37.5 ohm) termination), then the text on the LCD monitor is "bright" and looks like I expect it to look, but on the Axis video server, the text is more visible yet still unreadably dim.
So, my next check is to try a legitimate source, like a lipstick cam, which I'm going to try later today when I can get my hands on the camera.
Would the easiest fix, if the Demo Board is the problem, to put an op amp on the breadboard to drive the video out? I could also try an op amp on the output of the backpack. Is there a chip that is a self contained video amp with the proper impedances so I don't have to add external resistors, etc?
Thanks,
Chris
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-Phil